If the building block is lost it can be used as a replacement for assembly It is very practical and can be used to assemble and simulate the actual engine shape It can also be used to assemble large format MOC building block toysThe parts are made of high quality ABS plastic and are precision machined and cast They have no burrs and teeth The fit between the parts is excellent neither too tight nor too loose and there is a good experience in the use processThe product contains many special technology spare parts on the market compatible with LEGO technology The technology parts can be used interchangeable which is very suitable for MOC or when using other productsAll parts are brand new There are small items inside Use and place carefullyCustomer Service We replace missing or damaged parts for free